I have used the VLTOR action spring. I didn't find the Sprinco green action spring to be any smoother, but the green spring offers advantages I prefer. This isn't to take away from Buford's experience, nor to say mine outweighs his. Any quality rifle action spring will work.
Subjective reasons I find the Sprinco green spring to be optimal with 5.56 ammo-
-The VLTOR spring collapsed a bit. That may have to do with the fact I used the VLTOR spring to test an S&W MP10 308 which had an A5 style RE and came with a carbine weight buffer. I also used the green spring, but it didn't lose any length
-I just go to the Sprinco website to order new springs. I don't have to look around
-Sprinco spring rates seem to be consistent spring to spring
-Sprinco springs are color coded making spring identification easy
-Regardless of upper configuration, the A5 RE with A5H2 buffer & green spring gives me the softest recoil without compromising reliability. If there are problems, such as short stroking, stovepipes or bolt overs, I know it's the upper.
-The set-up has earned my trust
Last edited by MistWolf; 11-13-20 at 23:31.
The number of folks on my Full Of Shit list grows everyday
I am American
I was finally able to chrono some loads today from my 12.5:
Fed XM193: 2879
Wolf Gold: 2677
IMI 77 OTM: 2560
Speer Gold Dot 75gr: 2272
I'm happy with the XM193, but it looks like I'll need to find a faster expanding load.
Those are some really good numbers Jerry.
Today I was working on some load development with my 16 MPR. While I wasn't getting the velocities I wanted, I am gonna blame the powder for that. The flip side is that my best 5 shot group with the 77gr SMK's measured at 0.62" using ballistic-X software. I would post the pick but Imgur doesn't seem to be liking me at the moment. Multiple of the loads in the ladder test had a 3 shot clover leaf then a random 2 fliers. Still very impressed with the accuracy potential in this barrel with hand loads.
My load was as follows:
Win brass
Fed primer
H335 21.1gr-23.4gr (2425 FPS - 2580 FPS)
77gr SMK 2.260 OAL
Since I didn't get pressure signs I am gonna try up to a 24.x grain load and see if I can get to 2650 FPS and a nice group. One thing I found very interesting was how the gun was gassed. It felt like it really did live up to the hype of eating anything I fed it. The 21.1gr loads where incredibly anemic loads that made the action feel sluggish, yet it locked back every time. The 23.4gr loads are getting much closer to starting pressures for 556 and the gun was ultra flat shooting.
Over all I am very happy with my newest AR tube for the intended purposes.
Tactical Nylon Micro Brewery
Im starting to think that no barrel is magically faster than any others. Maybe in theory one might be a few fps faster because of rifling seal or whatever, but in practice it seems to be much more load dependent. For example both of these 12.5's had velocity numbers equivalent to my 16" with 77gr load. That doesnt mean the shorter tubes are just as fast, it means my load is just slow.
Also I would like to point out that it isn't fair to compare chrono numbers. Different shooters using a different chronograph, and shooting different lots of even the same load. For a truly fair comparison we gotta shoot all the guns on the exact same day, with the same chrono, and use the same load from the same lot of ammo. Otherwise we are drawing inaccurate conclusions from the data being presented.
Tactical Nylon Micro Brewery
Not from the chrono session, but I did get to shoot at 200 and 300 yards today on "paper" (electronic targets at the CMP range).
All 5 shot groups
At 200 yards:
Wolf Gold- 4.25"
XM193 - 6.3", 3.5", 4.6"
Magtech 77gr - 2.5"
IMI 77 - 2.25"
300 yards:
Wolf Gold- 9.2"
XM193- 8", 8"
Magtech 77 - 4.4"
All groups were shot with a YHM Turbo K attached. Very happy overall. Bulk ammo stays under 3 MOA and the 5.56 77gr stuff is under 1.5MOA. The ES measurements don't show it but the XM193 actually grouped really well with 4 out of 5 rounds being tight and 1 usually being an outlier.
Definitely agree that there is no special extra fast barrel. The 12.5 length definitely seems to deliver on useable velocity in a shorter package. For my purposes I'll stick with XM193 in this rifle for match use.
I have some Barnes 5.56 70gr en route that I'll be sure to chrono next. It will probably be my pig load if it comes close to the numbers I've seen other people report.
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